Table of Content

25 June 2019, Volume 30 Issue 12

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Dynamic Response and Anti Collision Devices of an Offshore Wind Turbine Subjected to Ship Impacts

HAN Zhiwei；ZHOU Hongjie；LI Chun；DING Qinwei；HAO Wenxing；YU Wan

2019, 30(12):  1387-1394. 

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In order to ensure the safety of supporting structures, 4 types protective devices were designed. A 3 MW wind turbine and ship collision model of monopole foundation was established based on conceptual design of the protective devices. Through LS-DYNA simulation of collision between ship with different impact velocities and wind turbine towers, dynamic response of tower with protective device in the collision processes was proposed and compared with that of conventional tower. The results show that without protective device, the towers in impacts have a big deformation, and stress will soon exceed the yield limit of material; compared with no protection device when the velocity of ship is as 1 m/s, 2 m/s, 3 m/s, structure deformations with type A protection device are 22.13%, 23.80% and 42.58%, and the maximum contact forces with type A protection devices are 54.38%, 54.95% and 63.92% respectively; combined protective devices have a better inhibitory effectiveness of wind turbine response.

Bolt Looseness Detection Using Piezoelectric Impedance Frequency Shift Method

SHAO Junhua1;WANG Tao1;WANG Zhengao2;WEI Denglai 1;LI Yourong2

2019, 30(12):  1395-1399,1408. 

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A piezoelectric impedance shift method was proposed to detect bolt looseness based on changes of piezoeletric impedance frcquency. A piezoelectric patch was bonded on the head of the bolt, and a material testing machine was adopted to apply tension force precisely on the tested bolt to simulate pre-tightening forces of bolts. The shift of a specified peak frequency in piezoelectric admittance spectrum was measured by a precision impedance analyzer in clean environments and oil pollution environments. The experimental results show that the specified peak frequency decreases while bolt preload increases, and the frequency shift has a linear relationship with the preload on the bolt, and oil pollution has a little effects on the experimental results.

Profile Division and Programmatic Modeling of Tetrahedral Truss Deployable Antennas

HAN Bo1;XU Yundou1,2;GUO Luyao1;ZHANG Shuo1;YAO Jiantao1,2;ZHAO Yongsheng1,2

2019, 30(12):  1400-1408. 

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Tetrahedral truss deployable antennas were studied,and a simple profile division method was proposed.Based on MATLAB and SOLIDWORKS,a programmatic modeling method was proposed. Custom software development for SOLIDWORKS was completed by VBA programming language,and visual operation interfaces were designed.Two examples of deployable antenna mechanisms were used to verify the correctness of the profile division method and the programmatic modeling processes.The proposed profile division method proposed herein is simple and the quality of the profile mesh is good,the method of programmatic modeling is convenient and quick to model the antenna mechanisms,and the overall design efficiency is greatly improved.

Effects of Flap on Aerodynamic and Noise Characteristics of Airfoils

YUE Minnan1;LI Chun1,2;HAO Wenxing1;ZHANG Junwei1

2019, 30(12):  1409-1416. 

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A fixed aerodynamic shrapnel was placed on NACA0018 airfoil suction surface, and the aerodynamic performance and noise characteristics of the original airfoils and the shrapnel airfoils were compared. A numerical simulation method was used to calculate the influences of aerodynamic elastic blades on the aerodynamic performance and noise characteristics of the airfoils when the angle of attack was from 6° to 24°. Results of the flow control mechanism analyses show that the pneumatic shrapnel has better effectiveness at high angle of attack and the lift. The coefficient is increased by 37.11%, the flow separation is slowed forward, and the airflow is improved. When the angle of attack is large, the pneumatic shrapnel may reduce the total sound pressure level of the airfoils at the receiving points, which will be reduced by 4.23%, and the total sound pressure level of the airfoil noise exhibits dipole characteristics in directivity distribution.

Design and Applications of Robotic Filament Winding CAD/CAM System

XU Jiazhong1;LIU Meijun1，2;SUN Dong1

2019, 30(12):  1416-1422. 

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Aiming at the problems that traditional winding machine was not fit for complex allotypic components filament winding, a filament winding CAD/CAM system was developed based on industrial robots. A local surface winding method was adopted to the filament winding pattern design of allotypic components. Based on the high order polynomial planning method for robot joint trajectory, the winding path of the robot with various motion forms was planned. One set of robotic filament CAD/CAM system was developed to realize pattern design of filament winding for allotypic component, filament winding path planning, automatic implementation of code file, and winding design process visualization. Winding test of the combined revolution verified the practicality of the system.

Leakage Analysis and Test of Internal and External Double-row Force Type Radial Piston Motor

WEN Desheng; SUI Guangdong;LIU Qiaoyan;LIU Xiaoxue

2019, 30(12):  1423-1428. 

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In order to extend the life of radial piston motors, a novel moter was designed based on principle of force couple. The formation of the coupler type motors was affected by the number of motor plungers and the number of cam ring guide curves. By analyzing the relationship between the number of motor plungers and the number of rail curve effects, the conditions under which the coupler motor might be formed were determined. The motor has a relatively moving friction pair in operations, and the relative movement of friction pair causes oil leakage. Taking the inner motor as an example, the leakage formula of the two places was determined by analyzing the leakage of the plunger in cylinder and the leakage of the distribution plate. The principle of the motor was tested to verify the correctness of the principle of the force-coupled radial piston motors.

A Fatigue Crack Detection Method Based on High-frequency Response Function

YAN Shaowen;QU Wenzhong;XIAO Li

2019, 30(12):  1428-1432,1479. 

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Aiming at the traditional structural health monitoring method using linear frequency response function which relied on the comparing with the undamaged structures and limited the application scopes, a fatigue crack damage identification method without a reference signatures of the undamaged structures based on nonlinear high-frequency response function. By considering the nonlinear natures of damage structures, this paper suggested to make use of the theory that the forced frequency response function of the cracked beams varied when the beams were excited at different amplitude excitation to extract nonlinear components without reference to form damage index to characterize nonlinear damages. Sensitivity of different frequency bands to detect fatigue cracks was also analyzed herein. The implemented experiments testify that this method may effectively identify fatigue cracks without a reference signature.

Nonlinear Processing for Vibration Displacement Systems of Continuous Casting Molds

LI Qiang1;FANG Yiming1,2;LI Jianxiong1;ZHENG Huicheng1

2019, 30(12):  1433-1440. 

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Taking the continuous casting mold vibration displacement systems driven by servo motors as research object, a nonlinear processing algorithm was proposed to deal with the nonlinear periodic function between eccentric shaft angles and mold vibration displacements. In the algorithm, the mapping between eccentric shaft angle error and mold displacement was established to ensure the uniqueness between motor rotations and mold displacements, which could reduce the complexity of controller design and the nonlinear influences on the control performance. Simulation and experimental results show the effectiveness of the proposed nonlinear processing algorithm.

Design of Subsonic Velocity and Airflow Temperature Controlled Wind Tunnel Test-bed

LI Yong1;LI Guowen2; WANG Weiming1;ZHAO Changhui1

2019, 30(12):  1441-1445. 

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A minitype opening high speed wind tunnel the test-bed was designed and researched, which was used to be as airflow simulation. The airflow temperature of wind tunnel might be controlled. On the basis of aerodynamics calefaction project design calculation,the software Fluent was adopted to optimize design parameters and the simulation of the flow fields in the test section was carried out. The calculation results of flow and temperature fields indicate that the wind tunnel test-bed design is right. Based on the optimizing design parameters,a high speed wind tunnel was made. Fact measurement indicates that the quality of wind tunnel flow fileds is well,and the test sect temperature accords with the design requests.

A Lateral and Longitudinal  Fuzzy Control of Intelligent Vehicles with Double Preview Points for Large Curvature Roads

DIAO Qinqing;ZHANG Yani;ZHU Lingyun

2019, 30(12):  1445-1452. 

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A lateral and longitudinal fuzzy control method of intelligent vehicles with dynamic double preview points was proposed herein to avoid early responses of steering system and ensure that the vehicles made a turn with a suitable speed in large curvature roads. A dynamic model as well as a kinetic model were established, and the safe speed for curvature roads was calculated. Then, the dynamic configuration of double preview points and the design of lateral and longitudinal fuzzy controller were presented. The results show that the double preview distance is regulated against the variation of curvature simultaneously, and the steering angle follows the reference path in a desirable accuracy keeping the speed within a safety range.

Regional Trajectory Planning of Unmanned Aerial Vehicles Based on Spiral Spline

CHEN Jie;DONG Wei;SHENG Xinjun;ZHU Xiangyang

2019, 30(12):  1453-1459. 

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A trajectory planning method was put forward based on spiral spline for the applications of unmanned aerial vehicles in regional operation. The method designed an algorithm to generate control points, and used NURBS for curve fitting. An optimization problem with the shortest flight time was solved by linear programming. The second-order Taylor expansion was used for curvilinear interpolation. Experiments were carried out on a platform with a trajectory tracking controller. From the experimental results it is shown that the method may effectively reduce flight time and improve efficiency, compared with traditional zigzag trajectory method under the same dynamic constraints and operation requirements.

Multi-information Intensity Characteristic State Assessment Method of Hydraulic Pums Based on Fault Mechanism

LIU Siyuan1，2，3;HE Yue1，2;LI Xiaoming4;LU Mingli3;LU Zhengdian3

2019, 30(12):  1460-1465,1473. 

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Taking the wear fault of hydraulic pump slipper as an example, a new method for assessing the status of multi-information intensity features was proposed based on fault mechanism. Starting from the wear mechanism of the slippers, this method divided the working states of the hydraulic pumps corresponding to the different wear degrees bused on of the slippers based on the compacting coefficients of the slippers. The intensity characteristic factors of pump vibrations, outlet flows and pressure signals were extracted by frequency domain calculation method of vibration intensity. The sensitivity of three intensity characteristic factors to the wear degrees of the slippers was analyzed, and the characteristic factor sample sets were established. The least squares method was used to fit the data to obtain the corresponding quantified relationship among the three intensity characteristic factors and the working states of the hydraulic pump. The BP neural network and D-S evidence theory were used to establish the state assessment model based on the multi-information decision fusion algorithm, and the validity of the model was verified by test samples. It indicates that the model has higher assessment accuracy.

Motion Mixed Control for Flexible-base and Flexible-joint Space Manipulators

CHEN Zhiyong;ZHANG Tingting

2019, 30(12):  1466-1473. 

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The control problems of a flexible-base and flexible-joint space manipulator with uncertainties were addressed, and a mixed control scheme was proposed based on adaptive robust terminal sliding mode control and adaptive optimal vibration control. Firstly, the system was reduced to a slow subsystem and a fast subsystem by singular perturbation method. Secondly, a trajectory-tracking adaptive robust terminal sliding mode control scheme, including an equivalent control, a robust control, and an adaptive adjusting algorithm, was presented for the slow subsystems. And then, a vibration optimal control strategy was proposed based on adaptive state observation for the fast subsystems. The simulation results show the validity of the proposed scheme in rigid and flexible motion controls of the system.

Classification and Identification of Multi-pattern of Hand Actions

DU Mingyu;WANG Zhiheng;XUN Yi;BAO Guanjun;GAO Feng;YANG Qinghua;ZHANG Libin

2019, 30(12):  1474-1479. 

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In order to meet the needs of many human hand action pattern recognitions in complex applications such as exercise rehabilitation training and human-machine interaction, influences of sEMG signals sampling channel layouts, training sample preparations, feature extraction modes, classifier structure parameters, and so on were analysed herein. Optimal signal sampling scheme was established, and 3 BP neural network classifiers were designed based on time domain statistic, self-regression model coefficient, and wavelet packet decomposition coefficient. Experimental results show that average recognition rate of classifiers for 6 kinds of single finger actions, 13 kinds of multi finger actions, 20 kinds of hand movements are 98.5%, 92.4%, and 90.9% respectively. Output delay is less than 190 ms, which verifies effectiveness and practicability of the proposed method.

Fruit Fly Optimization Algorithm for Solving Hybrid Flow-shop Scheduling Problems

DU Lizhen1;WANG Zhen1;KE Shanfu1;XIONG Zixue1;LI Xinyu2

2019, 30(12):  1480-1485. 

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To deal with hybrid flow-shop scheduling problems with unrelated parallel machines, weighted encoding was used for coding operations, according to the characteristics of population update method of fruit fly optimization algorithm. Weighting coefficients were added to improve random search ability of the algorithm. The algorithm parameters were analyzed, and the optimal parameter combination was obtained. Benchmarking examples were used for simulation verification, and the effectiveness of the fruit fly optimization algorithm was verified by comparison with classical algorithms.

Optimization Scheduling Approach for Units Marshalling in CRH Productions

GUO Jiapeng;ZHAO Ning;WU Xiuli

2019, 30(12):  1486-1492. 

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The CRH(China railway high-speed) units marshalling problem arised due to the difference orders of CRH productions and CRH delivery. Oriented to this problem, simulation model and a simple and practical heuristic scheduling was presented based on real CRH marshalling lines. Manufacturing processes corresponding to 3 different sizes were conducted. Based on the experiments, the proposed heuristic rule was compared with exhaustive algorithm, genetic algorithm, and stochastic rule. Experiments prove that the proposed heuristic rule may reach near optimal solutions quickly.

A Game-theory Based Optimization Approach for Job Scheduling in Virtual Manufacturing Networks

NIE Li1;ZHANG Guohui2;WANG Xiaogang1;BAI Yuewei1

2019, 30(12):  1492-1497. 

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A non-cooperative game model was put forward herein for job scheduling problems in virtual manufacturing networks, which transferred the problems into a game. The concept of D-minimum Nash equilibrium was proposed based on the analysis of the existence of ideal Nash equilibrium in game scheduling model. A Nash equilibrium solving method was proposed  based on genetic algorithm in order to search the D-minimum Nash equilibrium of the game. In the genetic algorithm, a chromosome coding and decoding scheme and fitness function were designed according to the characteristics of job scheduling problems in virtual manufacturing networks. Efficiency of the proposed approach was validated on several benchmark instances.


Cathode Design and Experimental Study of NC Electrochemical Boring Processes for Stepped Holes

XU Bo1,2;GAN Weimin1,2;HE Yafeng1,2;LI Wenjing3;WANG Xiangzhi1,2

2019, 30(12):  1498-1506. 

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NC electrochemical boring method was adopted to solve the processing problems of stepped inner holes with small inlet,large inner cavity,and large deep diameter ratio.According to the structural characteristics of stepped holes,cathodes with different spiral outlets,different rotating angles,and different taper of shunt blocks were designed.The flow fields were analyzed by FLUENT,and the results show that the cathodes with 24° conical angle,360° rotating angle,and double spiral outlets meet the design requirements.Orthogonal tests were carried out to study the influences of processing parameters on removal amount and processing clearance.Main size of the cathode is determined by the testing results,and the problems of uneven wall thickness of the stepped hole are solved by correcting the tapers of the cathodes.By the proposed method,errors of the stepped hole are small,and quality of processing surfaces is good,which meet the production requirements.

Property of Electromagnetic Welded Joints of 5052 Aluminum Alloy and HC420LA High Strength Steel in Salt Fog Corrosion

XU Bing1;OU Hang1;LIU Quanxiaoxiao1;XU Zhidan3;LI Guangyao1,2;CUI Junjia1,2

2019, 30(12):  1506-1511. 

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The salt fog corrosion tests of magnetic pulse welded joints of 5052 aluminum alloy and HC420LA high strength steel were conducted, and the corrosion mechanism of magnetic pulse welded joints was revealed. The research results show that the degradation of mechanical properties of welded joints under salt fog environments is very obvious, and the corrosion starts from the first weld tip. Welded joint remained 20% strength when the corrosion time comes to 48 h. Microstructure analysis of the fracture presents that the low potential of steel accelerates the corrosion rate, and the corrosion of welded joints has self-catalysis.